Soil retention, protection of natural and artificial structures, and increased land use are only a few reasons which motivate the use of landscape structures. For example, soil is often preserved on a hillside by maintaining the foliage across that plain. Root systems from the trees, shrubs, grass, and other naturally occurring plant life, work to hold the soil in place against the forces of wind and water. However, when reliance on natural mechanisms is not possible or practical, man often resorts to the use of artificial mechanisms such as retaining walls.
In constructing retaining walls, many different materials may be used depending on the given application. If a retaining wall is intended to be used to support the construction of a roadway, a steel wall or a concrete and steel wall may be appropriate. However, if the retaining wall is intended to landscape and conserve soil around a residential or commercial structure, a material may be used which compliments the architectural style of the structure such as wood timbers or concrete block.
Of all these materials, concrete block has received wide and popular acceptance for use in the construction of retaining walls and the like. Blocks used for these purposes include those disclosed by Forsberg, U.S. Pat. No. 4,802,320 and Design 296,007, among others.
Previously, blocks have been designed to "setback" at an angle to counter the pressure of the soil behind the wall. Setback is generally considered the distance in which one course of a wall extends beyond the front surface of the next highest course of the same wall. Given blocks of the same proportion, setback may also be regarded as the distance which the back surface of a higher course of blocks extends backwards in relation to the back surface of a lower course of the wall.
There is often a need in the development of structures such as roadways, abutments and bridges to provide maximum usable land and a clear definition of property lines. Such definition is often not possible through use of a composite masonry block which results in a setback wall. For example, a wall which sets back by its very nature will cross a property line and may also preclude maximization of usable land in the upper or subjacent property. As a result, a substantially vertical wall is more appropriate and desirable.
However, in such instances, vertical walls may be generally held in place through the use of mechanisms such as pins, deadheads, tie backs or other anchoring mechanisms to maintain the vertical profile of the wall. Besides being complex, anchoring mechanisms such as pin systems often rely on only one strand or section of support tether which, if broken, may completely compromise the structural integrity of the wall. Reliance on such complex fixtures often discourages the use of retaining wall systems by the everyday homeowner. Commercial landscapers may also avoid complex retaining wall systems as the time and expense involved in constructing these systems is not supportable given the price at which landscaping services are sold.
Further, retaining structures are often considered desirable in areas which require vertical wall but are not susceptible to any number of anchoring matrices or mechanisms. For example, in the construction of a retaining wall adjacent a building or other structure, it may not be possible to provide anchoring mechanisms such as a matrix web, deadheads or tie backs far enough into the retained earth to actually support the wall. Without a retaining mechanism such as a matrix web, tie-back, or dead head, many blocks may not offer the high mass per face square foot necessary for use in retaining structures which have a substantially vertical profile.
Manufacturing processes may also present impediments to structures of adequate integrity and strength. Providing blocks which do not require elaborate pin systems or other secondary retaining and aligning means and are still suitable for constructing structures of optimal strength is often difficult. Various measures must be taken depending upon the nature and position of the detail point on the block that is being made. Further, a balance between manufacturing ease and block performance.
Two examples of block molding systems are disclosed in commonly assigned Woolford et al, U.S. Pat. No. 5,062,610 and Woolford, U.S. patent application Ser. No. 07/828,031 filed Jan. 30, 1992 which are incorporated herein by reference. In both systems, advanced design and engineering is used to provide blocks of optimal strength and, in turn, structures of optimal strength, without the requirement of other secondary systems such as pins and the like. The Woolford et al patent discloses a mold which, through varying fill capacities provides for the uniform application of pressure across the fill. The Woolford application discloses a means of forming block features through the application of heat to various portions of the fill.
As can be seen there is a need for a composite masonry block which is stackable to form walls of high structural integrity without the use of complex pin and connection systems and without the need for securing mechanisms such as pins, or tie backs.